Campaigners have said they will seek a judicial review into a decision not to hold a public inquiry into the so-called Battle of Orgreave.
Home Secretary Amber Rudd told MPs a review into clashes between police and pickets during the 1984 miners’ strike was not in the public interest.
The Orgreave Truth and Justice Campaign (OTJC) told a press conference earlier “the gloves are off”.
Secretary Barbara Jackson said it may start crowdfunding to pay for a review.
“This has been four years of hard work, it’s taken over our lives,” she said at the Barnsley branch of the National Union of Mineworkers (NUM).
“The campaign has no intention of collapsing or folding. The gloves are now off on our side.”
Andy Burnham, MP for Leigh, asked an urgent question in the House of Commons about the decision.
He said Orgreave was one of the most divisive events in British social history, and that Prime Minister Theresa May “invited Orgreave campaigners to submit a bid for an inquiry”.
He said: “She entered Downing Street talking about fighting burning injustices. The House will understand why today so many people feel bitterly betrayed.
“Given there is evidence of unlawful conduct by police in relation to it, isn’t it simply staggering that the Home Secretary has brushed away an inquiry as not necessary?”
Mr Burnham asked Home Office minister Brandon Lewis whether Ms Rudd reviewed police files, cabinet papers and new testimony from police officers.
“If she didn’t do each and every one of these crucial things, won’t many people conclude that her decision-making process was incomplete and therefore unsound?” he said.
Mr Lewis said Ms Rudd had taken “a wide range of factors” into account.
In a letter to campaigners, Ms Rudd said policing had changed sufficiently in the years since Orgreave to mean an inquiry was not merited.
She added “ultimately there were no deaths or wrongful convictions” resulting from the conduct of South Yorkshire Police at the time.
Her decision has been condemned by former miners, Labour politicians and South Yorkshire’s Police and Crime Commissioner.
Speaking in the House of Commons, Dennis Skinner, MP for Bolsover, said: “Why is it that 31 years is too long for an inquiry, yet 31 years is not too long for this government to hide the Cabinet papers on the [miners] strike and refuse to release them?
“We now know that the Thatcher government was to close 75 pits and not 20.
“The truth is, this nasty party has now become the nasty government – more concerned about preserving the Thatcher government than it is fighting for truth and justice.”
Lawyer Michael Mansfield, who represented miners caught up in the violence at Orgreave, said campaigners calling for an inquiry into police tactics at the coking plant near Rotherham had been “sloughed off”.
He told the BBC’s Today programme Ms Rudd had overlooked an orchestrated campaign by South Yorkshire Police of “uncontrolled, unlawful violence” against miners.
“There has been no disciplinary proceedings and no prosecution [of South Yorkshire Police] at all over the years,” Mr Mansfield said.
“This does not reinforce public faith in the system and what is needed here is the restoration of confidence.
“It’s not about what happened, it’s really much more fundamental than that. How was this allowed to happen and why did it happen?”
The “Battle of Orgreave” was the most violent day of the year-long 1984-85 miners’ strike.
Huge lines of police clashed with striking miners as they tried to stop lorries carrying coke to fuel the Scunthorpe steel furnaces.
Violence erupted on both sides and at one stage police horses were sent to charge the crowd up the field as officers followed to make arrests.
Miner Chris Skidmore was at Orgreave and told BBC Radio Sheffield it was a “frightening experience”.
“It was chaos. The horses were chasing people, it was like a battle scene.
“There was no resemblance of any order or regimented formation. [The police] were everywhere, all over the field and road just hitting people.”
Dr Alan Billings, South Yorkshire Police and Crime Commissioner, said he had fully supported a public inquiry and was “absolutely devastated” and “in shock”.
“I think we’ve been led to believe there would be an inquiry, it was just a question of what form it would take,” he said.
“I think the Home Office and government have led us up to the top of the hill and down again and I really can’t understand that, they could have taken the decision two years ago.”
He said a public inquiry would have meant South Yorkshire Police could demonstrate it had moved on from the force’s “legacy issues”, including the Hillsborough and Rotherham child sex abuse scandals.
“We don’t fully know what happened at Orgreave, why it took this military-scale of activity, if it was somehow government-directed.
“It’s the point, I think, where the police come closest to being the instrument of the state and that’s a very dangerous place to be.
“We need to understand how that happened so we never get anywhere near that again.”
Chris Kitchen, national secretary of the NUM, accused Ms Rudd of trying to protect the Conservative Party in denying a public inquiry.
He said: “All [yesterday’s decision] has done is reinforce a long-held belief we’ve all had – that they have something to hide, and now we know it for sure,” he said.
Joe Rollin, chair of the OTJC, said: “That dismay and flabbergasted feeling is now turning into anger and we’re not going anywhere.”
A Home Office spokesman said: “The home secretary met the campaign and their supporters on 13 September to hear their concerns in person.
“She has told the OTJC that she considered a range of options in reaching her decision, but at no point did she ever commit to establishing any form of inquiry.”